'Cool it' for stored grain quality

Harvest time on Yorke Peninsula, SA

Wheat needs to be stored at or below 23 °C in Australia to inhibit quality changes in the resulting flour over the storage year.

So says CSIRO cereal chemist Peter Gras, whose work through the Cooperative Research Centre for Quality Wheat Products and Processes is backed by Weston Milling, Goodman Fielder and Arnott's Biscuits as well as by growers and the Federal Government through the GRDC.

"Commercial bakeries in Australia complain of changing baking characteristics in flour at different times of the year, primarily manifested in increased mixing time as the year progresses," says Dr Gras says. "Dough becomes progressively stronger from immediately after harvest — say October — through to the following September.

"Wheat stored at 30°C or above shows significant deterioration in quality over the storage year and, for bakeries, that means increased dough development time, reduced water absorption by flour, and smaller volume and increased firmness in baked products."

Dr Gras says commercial bakeries have limited ability to increase mixing time because of their tight production schedules, and have to rely on changes in dough formulation like cutting back the amount of water used. But a 2 per cent reduction in water absorption — requiring more flour — means a 1.2 per cent increase in ingredient costs, as well as making the dough suffer and the bread firmer.

1,000% benefit to growers

Grain needs to be cooled to 23°C within 10 weeks of harvest — ideally at harvest in hotter areas like Queensland and northern New South Wales — and the practical way to achieve this is by aeratior Aeration has practical benefits for grain handlers as well as the millers and bakers downstream. It reduces the need for pesticides, improves efficiency, reduces moisture migration and can be fitted to old silos. At a total, added, annual cost of around 50c/t of stored grain, taking average losses into account, there's a $10 return for each $1 growers spend on aeration — a 1,000% benefit.

Program 1.2.3 Contact: Dr Peter Gras 02 9490 8408

Region North